The Doomsday Bug

Body snatcher targets mud crabs

By Sandra Olivetti Martin

When it comes to horror, Mother Nature stands at the top of the class.
Our Halloween Creature Feature comes from the Smithsonian Environmental Research Center in Edgewater, where scientists have a horribly resourceful parasite under their microscopes. With devilish ingenuity, it takes over its host’s reproductive system for its own replication.
Loxothylacus panopaei (Loxo for short) is a “highly evolved” barnacle preying on white-fingered mud crabs, a Chesapeake species.
In the 1960s, Loxo was transported to the Chesapeake from the Gulf Coast by way of oysters imported to restore the Bay population, SERC director Anson Hines reports. Larval females burrow into molted crabs and take over like body snatchers. Egg sacs emerge through the crab’s abdomen to await fertilization by a free-swimming male.
“This process eliminates the crab’s ability to reproduce and results in the crab caring for the developing larvae of the parasite,” the Smithsonian reports.
Loxo “could eventually reach a species-destroying high,” Hines says, as each infected crab releases thousands of larvae into the water to seek new crab hosts.
The good news in this horror story: Loxo has no use for blue crabs.
The bad news: Its first cousin does, although that perilous bug has not migrated from its native Gulf waters.
But “it has opportunities,” Hines says. “Things are introduced all the time, deliberately or through ballast water.”